Abstract: A pyrazine derivative of the following formula (I): wherein R1 is hydrogen or optionally substituted lower alkyl; X is hydrogen, halogen, hydroxy, cyano, acyl, or amino, aryl, heterocyclic group or the like; Y is hydrogen, halogen, hydroxy, acyl, amino, or the like; Z is aryl or heteroaryl, each of which is optionally substituted; or a salt thereof. The pyrazine compound (I) and a salt thereof of the present invention are adenosine antagonists and are useful for the prevention and/or treatment of depression, dementia (e.g. Alzheimer's disease, cerebrovascular dementia, dementia accompanying Parkinson's disease, etc.), Parkinson's disease, anxiety, pain, cerebrovascular disease (e.g. stroke, etc.), heart failure and the like.

Abstract: A pyrazine derivative of the following formula (I): wherein R1 is hydrogen or optionally substituted lower alkyl; X is hydrogen, halogen, hydroxy, cyano, acyl, or amino, aryl, heterocyclic group or the like; Y is hydrogen, halogen, hydroxy, acyl, amino, or the like; Z is aryl or heteroaryl, each of which is optionally substituted; or a salt thereof. The pyrazine compound (I) and a salt thereof of the present invention are adenosine antagonists and are useful for the prevention and/or treatment of depression, dementia (e.g. Alzheimer's disease, cerebrovascular dementia, dementia accompanying Parkinson's disease, etc.), Parkinson's disease, anxiety, pain, cerebrovascular disease (e.g. stroke, etc.), heart failure and the like.

Abstract: A beta-alanine derivative of the formula (I) wherein R1 is hydrogen atom or an amino protective group; A is a lower alkylene group or a lower alkenylene group; R2 is hydrogen atom or an amino group which may be substituted with an acyl group; R3 is hydrogen atom or an aryl or aralkyl group which may be substituted with one or more of hydroxy and/or lower alkoxy, a moiety represented by the formula (II), which is a bivalent N-containing 6- to 8-membered heterocyclic group, or a pharmaceutically acceptable salt thereof.

Abstract: A pyrazolopyridine compound of formula (I) wherein: R1 is hydrogen, lower alkyl optionally substituted by susbtituent(s), or cyclo(lower)alkyl which may be interrupted by an oxygen or nitrogen atom and optionally substituted by substituent(s); R2 is hydrogen, halogen or lower alkoxy; R3 is a substituent; and n is an integer from 1 to 4, provided R3 may be different from each other when n is 2, 3 or 4, or a salt thereof. The pyrazolopyridine compound (I) and salt thereof of the present invention are adnosine antagonists and are useful for the prevention and/or treatment of depression, dementia (e.g. Alzheimer's disease, cerebrovascular dementia, dementia accompanying Parkinson's disease, etc.) Parkinson's disease, anxiety, pain, cerebrovascular disease (e.g. stroke, etc.), heart failure and the like.

Abstract: A beta-alanine derivative of the formula (I) wherein R1 is hydrogen atom or an amino protective group; A is a lower alkylene group or a lower alkenylene group; R2 is hydrogen atom or an amino group which may be substituted with an acyl group; R3 is hydrogen atom or an aryl or aralkyl group which may be substituted with one or more of hydroxy and/or lower alkoxy, a moiety represented by the formula (II), which is a bivalent N-containing 6- to 8-membered heterocyclic group, or a pharmaceutically acceptable salt thereof.

Abstract: A compound of the formula: wherein R1 is hydrogen or halogen, R2 is hydroxy, acyl(lower)alkoxy, hydroxy(lower)alkyl, lower alkoxy(lower)alkyl, lower alkylthio(lower)alkyl, mono(or di or tri)halo(lower)alkyl, (ethoxycarbonyl)amino, sulfamoylamino, (dimethylsulfamoyl)amino, N,N-di(lower)alkylamino(lower)alkyl, hydroxyimino(lower)alkyl, lower alkoxyimino(lower)alkyl, acyl, lower alkoxycarbonyl, carbamoyl, di(lower)alkylcarbamoyl, (amino(lower)alkyl)carbamoyl, N,N-di(lower)alkylamino(lower)alkylcarbamoyl, guanidinocarbonyl, morpholinylsulfonyl, sulfamoyl, lower alkylsulfamoyl, (lower alkylsulfonyl)(lower)alkyl, guanidinocarbonyl(lower)alkenyl, lower alkylthio, cyano, acyl(lower)alkyl, acyl(lower)alkenyl, aryl which has one or more substituent(s) or a heterocyclic group which has one or more substituent(s), and X is —O—, or a salt thereof.